Applied Physics A (2025) 131:852
h ps://doi.o g/10.1007/s00339-025-09031-7
pos -annealing samples in an oxygen- ich en i onmen sig-
ni ican ly educed hei magne ic o de ing [2, 3].
A heo e ical s udy conduc ed a ew yea s ago sugges ed
ha in TiO2 and SnO2, FM a ises om oxygen acan-
cies [8]. I was demons a ed ha acancy si es in hese
oxides induce spin spli ing wi h a high-spin s a e, and he
exchange in e ac ion be ween he elec ons su ounding he
acancy and he local symme y ield esul s in a e omag-
ne ic g ound s a e [8]. The nanoscale size o hese ma e ials,
along wi h quan um con inemen e ec s, plays a c ucial ole
in hei magne ic p ope ies [8, 9]. Room- empe a u e FM
has been epo ed in p is ine SnO2 ilms [3, 7] as well as in
SnO2 nanopa icles [5].
X- ay abso p ion spec oscopy (XAS) measu emen s
indica e ha su ace- ela ed de ec s exhibi a magne ic
iple g ound s a e, whe eas he bulk SnO2 g ound s a e
emains in a non-magne ic single s a e [6]. O he s udies
on SnO2 nanopa icles wi h special oxygen ea men s sug-
ges ha FM is p edominan ly a su ace e ec [10, 11]. In
esea ch in ol ing TM, mul iple s udies ha e shown ha
nei he he ype o dopan no i s concen a ion signi ican ly
a ec s he Cu ie empe a u e (TC), leading o he conclusion
ha TM doping is no he p ima y cause o FM in hese
ma e ials [12].
Recen s udies on SnO2 ilms sugges ha hei FM
beha io is inhe en ly wo-dimensional (2D), ein o cing
1 In oduc ion
Ha ing bo h cha ges and spins in one compound, and being
conside ed as po en ial candida es o spin onic applica-
ions, magne ic semiconduc ing oxides ha e ga ne ed sig-
ni ican a en ion. The obse a ion o he oom empe a u e
e omagne ism (FM) in undoped semiconduc ing oxides
in nanos uc u es [1–5] has been ega ded as a ema kable
phenomenon in he ield o magne ism. The ques ion o he
o igin o he obse ed FM has been aised. Since hese ma e-
ials lack ansi ion-me al (TM) doping, he obse ed FM
canno be a ibu ed o double-exchange (DE) in e ac ions
[1–7]. Ins ead, oxygen acancies and de ec s a e belie ed o
be he p ima y cause o he e omagne ic beha io o p is-
ine semiconduc ing oxides. Suppo ing his assump ion,
Nguyen Hoa Hong
[email p o ec ed]
1 Depa men o Condensed Ma e Physics, Facul y o
Science, Masa yk Uni e si y, Ko lářská 2, B no
61137, Czechia
2 Depa men o Ma hema ics and Physics, Ma shall
Uni e si y, One John Ma shall D i e, Hun ing on 25755,
WV, US
Abs ac
We in es iga e he o igin o e omagne ism (FM) and he excep ionally high Cu ie empe a u e (TC) in undoped SnO2
ilms. Ul a- hin SnO2 ilms we e ound o exhibi signi ican FM, while hicke ilms show a diamagne ic beha io . S uc-
u al and chemical analyses e eal a a ia ion in oxygen acancy concen a ions be ween hin and hick ilms. No ably, an
excep ionally high TC exceeding 800 K is obse ed o he i s ime. XPS and XAS analyses e eal he p esence o oxygen
and in acancies, which migh play a c ucial ole in he obse ed magne ism. Theo e ically, i was supposed ha oxygen
acancies play a c ucial ole in he FM o SnO2 ilms. Howe e , he expe imen ally obse ed TC su passes he p edic ed
505 K, sugges ing addi ional con ibu ing ac o s. This sugges s ha bo h oxygen and in de ec s migh con ibu e o he
o al magne ic momen . The indings highligh he key ole o de ec -induced magne ism in SnO2 hin ilms and p o ide
insigh s in o he undamen al mechanism d i ing high- TC FM in undoped oxide semiconduc o s.
Keywo ds Su ace- ela ed e omagne ism · High TC · Low dimensionali y · Spin onics
Recei ed: 5 Augus 2025 / Accep ed: 2 Oc obe 2025
© The Au ho (s) 2025, co ec ed publica ion 2025
P is ine SnO2 hin ilms: o igins o high Cu ie empe a u e
Nguyen SyPham1· Nguyen QueHuong2· Pe Pazou ek1· Mojmi Meduna1· Ond ejCaha1· Nguyen HoaHong1
1 3
N. S. Pham e al.
he hypo hesis ha i is su ace- ela ed [13]. Rega ding he
TC o dilu ed magne ic semiconduc ing oxides, alues o
app oxima ely 880 K ha e been epo ed o TiO2 ilms [4],
howe e , o da e, no TC alue has been epo ed o undoped
SnO2 ilms, ega dless o he ab ica ion me hod used.
In his s udy, we will examine he TC o SnO2 ilms and
ela ed issues. Addi ionally, we will discuss he o igin o
FM in ul a- hin SnO2 ilms and compa e ou indings wi h
heo e ical p edic ions.
2 Expe imen
SnO2 ilms we e deposi ed using a Pulsed-Lase Deposi ion
(PLD) sys em (K F, 248 nm) om a SnO2 ce amic a ge
on o (100) LaAlO3 (LAO) subs a es. The deposi ion was
pe o med wi h an ene gy densi y o 2 J/cm² and a epe i ion
a e o 10 Hz. The op imized g ow h condi ions included a
subs a e empe a u e o 650 °C, an oxygen p essu e o 0.01
mba , and an O2:A low a io o 50:50. The ypical ilm hick-
ness anged om 50 nm o 340 nm. All SnO2 ilms appea ed
shiny and highly anspa en . S uc u al cha ac e iza ion was
conduc ed using X- ay di ac ions (XRD) a oom empe -
a u e. Magne ic momen (M) as a unc ion o he magne ic
ield (H) (0 o 0.5 T) and empe a u e (T) (50 K o 900 K) was
measu ed using a VSM magne ome e . X- ay Pho oelec on
Spec oscopy (XPS) was used a oom empe a u e o de e -
mine he chemical s a es. The magne ic ield was applied bo h
pa allel and pe pendicula o he ilm plane. The hickness o
ypical ilms was measu ed using a NIR-UV spec oscopic
ellipsome e J.A. Woollam V-VASE in he wa eleng h ange
o 400 o 1000 nm, wi h he Cauchy me hod used o hick-
ness de e mina ion. Film mo phology and chemical compo-
si ion we e analyzed using Scanning Elec on Mic oscopy
(SEM TESCAN LYRA 3) and ene gy-dispe si e spec os-
copy (B uke XFlash 5010), wi h SEM images cap u ed a a
5 kV accele a ing ol age. Fu he s uc u al in es iga ions o
ilms wi h a ying hicknesses we e ca ied ou using X- ay
Re lec i i y (XRR) and X- ay Abso p ion Spec oscopy
(XAS) a oom empe a u e, conduc ed a beamline PM3 o
he BESSY II Synch o on cen e . Addi ionally, he d ain sig-
nal was measu ed a an incidence angle o 4.5°.
3 Theo y
We use he igh -binding o linea combina ion o molecula
o bi als (LCMO) me hod [8] o explo e he possibili y o
FM and TC in SnO2 due o oxygen acancies in 2D con igu-
a ions. FM and high TC ha e been obse ed only in hin
ilms, no in bulk ma e ials, sugges ing ha he 2D con igu-
a ion plays a c ucial ole.
The Sn a om has an elec onic con igu a ion o
[4d105s25p2], whe e he 2 5s- and 2 5p- elec ons pa icipa e
in bonding wi h oxygen, esul ing in a Sn4+ ion wi h a closed-
shell [Pd]4d10 con igu a ion, wi h no unpai ed elec ons. In
he u ile e agonal local symme y D4h o SnO2 molecule,
each wo o Sn a oms a e su ounded by six oxygen a oms
[14]. I an oxygen acancy occu s, he 2p elec ons lose
hei bonding bu emain in he shell, o ming a p2 impu i y
cen e . The exchange in e ac ion among hese p-elec ons,
as well as hei in e ac ion wi h he molecula o bi al in he
local e agonal symme y, al e s he ene gy s a es, inc ease
he ene gy and modi ies he magne ic momen , e en ually,
a ec ing TC.
The wo p-elec ons, each occupying a wo- old degen-
e a e e-o bi al, couple wi h each o he o o m a con-
igu a ion ep esen ed by he p oduc decomposi ion
E×E=A1+A2+E
h ough he educ ion p ocess
[15, 16]. The wa e unc ions o he wo coupling E-o bi als
could be w i en as.
e
2
,
1
A
1
,M
s=0⟩
,
e
2
,
3
A
2
,M
S=1⟩
,
e
2
,
3
A
2
,M
s=0⟩
,
e
2
,
3
A
2
,M
S=−1⟩
o
1A1
and
3A2
o bi als; and
|e2,1Eu, Ms=0⟩,|e2,1E ,Ms=0⟩
o
1E
o bi al, co esponding o
Ms=0
and
Ms=1
,
while sa is ying he Pauli exclusion p inciple.
Since oxygen is a ou - alence anion, he absence o
one oxygen a om c ea es ou addi ional elec ons in he
impu i y band. Being a ound a acancy cen e , an elec on
would in e ac wi h he impu i y band h ough Coulomb and
exchange in e ac ion, gi en by
Hex =−JSIse
whe e SJ is he o al spin o he impu i y con igu a ion, se
is he spin o he elec on, and J is he exchange ma ix ele-
men , which consis s o adial and angula componen s.
To accoun o he hin- ilm con igu a ion, we impose s ong
con inemen o wa e unc ions along he z-axis. This con ine-
men localizes he elec ons u he , inc easing hei sensi i i y
o local symme y and enhancing he exchange in e ac ion.
Using he mean- ield app oxima ion
kBTc=
2
3
∑
ij
Jij
including he exchange in eg als a oxygen acancy si es,
we ob ained 𝑘𝐵𝑇𝑐 a ound 6.95 × 10−21, co esponding o
he TC o abou 505 K.
1 3
852 Page 2 o 9
P is ine SnO2 hin ilms: o igins o high Cu ie empe a u e
4 Resul s and discussions
X- ay di ac ion (XRD) pa e ns o ou SnO2 ilms and a
ba e LaAlO3 subs a e a e shown in Fig. 1. SnO₂ ilms wi h
di e en hicknesses all exhibi a single-phase s uc u e wi h
dis inc (200) and (101) peaks in he di ac og ams. All he
di ac ion peaks including (101), (200) can be a ibu ed o
e agonal u ile s uc u e o SnO2 and well ma ches wi h
JCPDS ca d No. 41–1445 [17]. The p esence o hese peaks
is signi ican and will be discussed la e in he con ex o
e i ying he magne ic aniso opy o he SnO2 ilms. The
mo phology o a ypical SnO₂ hin ilm is displayed in Fig.
2, demons a ing i s high homogenei y. Addi ionally, EDS
mapping (Fig. 2b–d) e eals a uni o m dis ibu ion o O and
Sn elemen s ac oss he ilm. Fu he s uc u al in es iga-
ions o he SnO2 ilms we e conduc ed using XRR mea-
su emen s. To enable XAS measu emen s, SnO2 ilms o
a ying hicknesses we e coa ed wi h a hin ca bon laye
o a ew nanome e s. In ou analysis, dSnO2 ep esen s he
hickness o he SnO2 laye , while dC deno es he hickness
o he ca bon coa ing, bo h ob ained om simula ions using
GenX so wa e [18]. The oughness pa ame e (σ) co e-
sponds o he highes in e ace oughness alue de e mined
om hese simula ions.
The XAS measu emen s we e pe o med a 280 K, close
o he Sn abso p ion edge (484.9 eV), using X- ays wi h an
ene gy o 480 eV. As seen in Fig. 3, when simula ed wi h
XRR da a, he 50 nm- and 100 nm- hick SnO2 ilms exhibi
a hickness ha is sligh ly smalle han he objec i e hick-
ness. Howe e , when accoun ing o he ca bon coa ing, he
o al hickness closely ma ches each o he . The SnO2 ilms
a e gene ally ough, wi h he oughness de e mined o be
(2.8 ± 0.4) nm o he 100 nm- hick ilm and (2.5 ± 0.5) nm
o he 50 nm- hick ilm.
The M(H) cu es o magne iza ion e sus magne ic ield
o he 74 nm- hick SnO₂ ilm a e shown in Fig. 4(a). The
magne ic ield was applied ei he pa allel o pe pendicula
o he ilm plane. The inse s show he magni ied iews o
hese cu es, allowing a clea e obse a ion o coe ci i y
(HC). Ou SnO2 hin ilms exhibi so magne ic beha -
io wi h a small HC. The 74 nm- hick SnO2 ilm demon-
s a es a ema kably la ge sa u a ed magne iza ion (Mₛ), i.e.
almos an o de o magni ude g ea e han he highes p e-
iously epo ed alue o SnO2 [3]. Compa ing wi h he
same ilmed being measu e a yea ea lie , Mₛ dec eased by
only 20% o e a one-yea ime, indica ing minimal aging
e ec s and sugges ing ha he ilms a e du able enough o
de ice applica ions. In e es ingly, despi e he di e ence in
Ms when measu ed in he pe pendicula con igu a ion, he
ilm main ains e omagne ic abo e oom empe a u e. This
obse a ion aligns wi h some heo e ical modeling, which
sugges s ha oxygen and in de ec s may induce e omag-
ne ic o de ing along ce ain axes while p omo ing a mixed
e omagne ic- e imagne ic s a e along o he s [13]. This
Fig. 1 XRD pa e ns o SnO-
2 ilms wi h di e en hicknesses
deposi ed on LaAlO3subs a e
and o a ba e LaAlO3subs a e
1 3
Page 3 o 9 852
N. S. Pham e al.
Fig. 3 XRR da a and simula-
ions o SnO2 ilms wi h nominal
hicknesses o 50-100 nm co -
e ed by C. dSnO2deno es he hick-
ness o he SnO2 laye ; dC ep e-
sen s he C op laye hickness;
he σ ep esen s he highes
oughness alue o he in e aces
ob ained om simula ions
Fig. 2 a) SEM image o he 74
nm- hick SnO2 ilm; b) gene al
colo mapping esul o SnO2
ilm; c) O colo mapping; d) Sn
colo mapping
1 3
852 Page 4 o 9
P is ine SnO2 hin ilms: o igins o high Cu ie empe a u e
as well as hei ela i e dis ances, i can explain why mag-
ne iza ion is no dependen linea ly on he ilm hickness.
The hin laye s nea o he su ace p ima ily dic a e he
magne ic p ope ies o SnO2, and he e exis s a c i ical line
dis inguishing e omagne ic and e imagne ic beha io . In
50 nm -and 100 nm- hick ilms, a diamagne ic beha io was
de ec ed when he magne ic ield applied pe pendicula o
he ilm’s plane, con i ming he exis ence o aniso opy in
his amily o ma e ials, and i well sugges s ha he FM in
his ilms mos p obably has he o igin om de ec s and/o
acancies. The FM in SnO2 ilms is well in-plane.
The XPS spec a o O1s o 74 nm - hick SnO2 ilm and
he 340 nm- hick SnO2 ilm a e shown in Fig. 5. While XPS
cha ac e is ic is also e iden in he M-H da a o ilms o
a ying hicknesses, as shown in Fig. 4(b). Table 1 lis s he
Mₛ alues o all s udied ilms, e ealing ha he 50 nm- hick
ilm exhibi s an Mₛ o app oxima ely 9 emu/cm³, lowe han
ha o he 74 nm- hick ilm, while he Mₛ o he 100 nm-
hick ilm is also smalle . I he o al magne ic momen o
SnO2 depends on he p ecise loca ions o O and Sn de ec s,
Table 1 Sa u a ed magne iza ion o SnO2 ilms wi h di e en hick-
nesses
Thickness (nm) 50 74 100 340
Sa u a ed magne iza ion (emu/cm3)9 78 3 < 0
Fig. 5 Analysis o chemical s a es om high esolu ion XPS spec a o (a) O1s o he 74 nm- hick SnO2 ilm; (b) O1s gene al o he 340 nm- hick
Fig. 4 Field dependence o magne iza ion aken a 300 K o (a) he
74 nm- SnO2 ilm wi h magne ic ield applied pa allel and pe pendicu-
la o he ilm plane. The inse s a e zooms o he wo M-H cu es o
e eal HC; and (b) o he 50 and 100 nm- hick SnO2 ilms wi h mag-
ne ic ield applied pa allel and pe pendicula o he ilm plane
1 3
Page 5 o 9 852
N. S. Pham e al.
XAS da a o SnO2 hin ilms a e shown in Fig. 7. The
abso p ion spec a a he O edge and Sn edge a e shown
in Fig. 7(a) and Fig. 7(b), espec i ely. Ce ain di e ences
a e obse ed be ween he spec a o he 50 nm- hick and
100 nm- hick ilms. In gene al, quan um con inemen
e ec s in e y hin ilms can induce shi s in he abso p-
ion edge. Addi ionally, su ace and in e ace s a es may sig-
ni ican ly in luence elec onic ansi ions in hinne ilms.
The 50 nm- hick ilm is likely o ha e a highe densi y o
de ec s compa ed o he 100 nm- hick ilm, which can lead
o modi ica ions in he abso p ion edge. Such shi s shi in
he abso p ion edge o ilms wi h di e en hicknesses indi-
ca e a ia ions in he bandgap ene gy, as epo ed in Re
[6]. Di e ences in he abso p ion spec a a bo h he O and
Sn edges ha e been obse ed, con i ming ha he hin and
hick ilms exhibi di e en de ec densi ies whe he due o
O o Sn acancies, esul ing in a ia ions in hei bandgap
ene gies. The Sn-M4,5 abso p ion edges (3d3/2 and 3d5/2) dis-
play a cha ac e is ic double s uc u e wi h a ela i e shi o
2.1 eV, co esponding o wo oxida ion s a es o Sn. This
obse a ion ag ees well wi h he XPS analysis abo e (Fig.
6) and he co esponding magne iza ion da a. The p es-
ence o Sn acancies and de ec s is e iden ly linked o he
epo ed magne ic momen in hese ilms.
mos ly p o ides su ace-sensi i e da a, i emains ele an
since magne ism in SnO2 ilms is la gely su ace- ela ed,
and he XPS da a s ill can e lec well he conce ned p ope -
ies o he ilm.
Figu e 5(a) shows a b oad peak in he O spec um o he
74 nm- hick SnO2 ilm, which can be cu e- i ed in o wo
peaks wi h binding ene gies o app oxima ely 529.2 eV and
530.5 eV espec i ely. The o me ep esen s la ice oxygen
(OL) in he SnO2 c ys al s uc u e, while he la e co esponds
o oxygen acancies (OV) on he ilm su ace. Simila ea u es
ha e been epo ed o O acancies in SnO2 [19]. To compa e
how oxygen acancies can be di e en o ilms wi h di e -
en hicknesses, XPS measu emen s we e also conduc ed on
he diamagne ic 340 nm- hick SnO2 ilm, as shown in Fig.
5(b). No ably, he e omagne ic 74 nm- hick ilm exhibi s a
highe concen a ion o oxygen acancies compa ed o he
diamagne ic 340 nm- hick ilm, as e iden om Fig. 6. Addi-
ionally, he chemical s a e o Sn in he 74 nm- hick SnO2 hin
ilm was u he analyzed using XPS (Fig. 6). The decon o-
lu ions o he Sn 3d3/2 and Sn 3d5/2 peaks e eal ou dis inc
peaks: hose a 495.26 eV and 486.85 eV co espond o Sn4+
s a es, while he peaks a 493.39 eV and 484.76 eV a e a ib-
u ed o Sn2+ s a es [20] The ma e ial composi ion is no ably
domina ed by Sn4+ s a es [21].
Fig. 6 XPS spec um o he Sn
3d3/2 and Sn 3d5/2 peaks o he
74 nm- hick SnO2 ilm
1 3
852 Page 6 o 9
P is ine SnO2 hin ilms: o igins o high Cu ie empe a u e
SnO2 ilm o he e omagne ic phase a a ound 818 K. In
discussions ega ding dilu ed magne ic semiconduc o s, i
has been well es ablished ha TC is o en independen o he
ype o dopan o doping concen a ion [12]. Fo undoped
semiconduc ing oxides, also known as d0 magne ism, whe e
no 3d elemen doping is p esen (i.e. no DE in e ac ion can
occu ), p edic ing TC is pa icula ly challenging. Theo e i-
cally, TC can be e alua ed as:
TC
=2J
e
Z[s[s+1]]
3kB
[22],
The magne iza ion e sus empe a u e cu e o he 74
nm- hick SnO2 ilm, aken a 2 T, is shown in Fig. 8. No a-
bly, an excep ionally high Cu ie empe a u e o 850 K is
obse ed o he i s ime. The SnO2 ilm ansi ions in o a
e omagne ic phase a app oxima ely 850 K, as indica ed
by he in e sec ion o he M(T) cu e wi h he T-axis and
main ains e omagne ic o he whole ange o empe a u e
below 850 K. To de e mine TC mo e p ecisely, he dM/dT
s. T plo is also inse ed in o Fig. 8. A dis inc minimum a
818 K in his plo con i ms he ansi ion empe a u e o ou
Fig. 8 Magne iza ion e sus em-
pe a u e aken a 2 T o he 74
nm- hick ilm (magne ic ield was
applied pa allel o he ilm plane).
The inse shows hedM/dT s T
cu e
Fig. 7 Abso p ion spec a seen om a) O edge and b) Sn edge o 50 nm- hick and 100 nm- hick ilms o SnO2
1 3
Page 7 o 9 852
N. S. Pham e al.
he inancial suppo o he measu emen s and sample ab ica ion a
he Cen al Eu opean Ins i u e o Technology (CEITEC). We hank
Synch o on Bessy II o le ing us use hei acili y and To s en
Kachel o assis ance.
Au ho con ibu ions N. H. Hong’s ole in ol es ob aining he und-
ing, concep ualiza ion, coo dina ing he wo k, supe ising, in e p e -
ing da a, and w i ing he a icles. P. Pazou ek made he ilms. N. S.
Pham ca ied ou he XRD, VSM, XPS, and SEM measu emen s and
analyzed da a and plo ed igu es. N. Q. Huong was in cha ge o he
heo e ical wo k and w o e he pa in he a icle as well as edi ing he
manusc ip . M. Meduna and O. Caha pe o med he XRR and XAS
measu emen s and analyzed ela ed da a. All au ho s checked and ed-
i ed he inal e sion o he manusc ip .
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Re e ences
1. M. Venka esan, C.B. Fi zge ald, J.M. Coey, D. „ unexpec ed mag-
ne ism in a dielec ic oxide. Na u e. 430, 630 (2004)
2. N.H. Hong, J. Sakai, N. Poi o , V. B izé, Room- empe a u e e -
omagne ism obse ed in undoped semiconduc ing and insula ing
oxide hin ilms. Phys. Re . B 73, 132404 (2006)
3. N.H. Hong, N. Poi o , Sakai, „ e omagne ism obse ed in p is-
ine hin ilms. Phys. Re . B 77, 33205 (2008)
4. S.D. Yoon, Y. Chen, A. Yang, T.L. Good ich, X. Zuo, D.A. A ena,
K. Zieme , C. Vi o ia, Oxygen-de ec -induced magne ism o 880
K in semiconduc ing ana ase TiO. Films. J. Phys. Condens. Ma -
e . 18, L355–L361 (2006)
5. A. Sunda esan, B. Bhag a i, N. Ranga ajan, U. Siddesh, C.N.
Rao, R., e omagne ism as a uni e sal ea u e o nanopa icles o
he o he wise nonmagne ic oxides. Phys. Re . B 74(R), 161306
(2006)
6. G.S. Chang, J. Fo es , E.Z. Ku mae , A.N. Mo ozo ska, M.D.
Glinchuk, J.A. McLeod, A. Moewes, T.P. Su ko a, N.H. Hong,
whe e Je is he exchange in eg al, S = 1 indica ing a single
elec on, and Z is he numbe o nea es neighbo ing acan-
cies, and kB is Bol zmann cons an .
F om ou XPS da a, o he 74 nm- hick- ilm, we es ima e
ha each Sn a om has app oxima ely h ee nea es neighbo -
ing oxygen acancies, based he Sn/O and he OL/OV a ios.
Using a Cu ie empe a u e TC, o 818 K, spin S = 1, and
Z = 3, we apply he abo e o mula o es ima e he exchange
in eg al o SnO2 as abou 2.89 × 10−21 J. This alue is o he
same o de o magni ude as he exchange in eg al o ansi-
ion me als, which is ypically a ound 10−21 J [23].
When conside ing only oxygen acancies in a low-dimen-
sional SnO2 sys em, TC was ini ially es ima ed o be 505 K,
as men ioned ea lie , heo e ically. Howe e , he expe imen-
ally obse ed TC in ou SnO2 ilms is signi ican ly highe
(> 800 K). This disc epancy migh be well explained by
he p esence o addi ional Sn acancies/de ec s, which e i-
den ly exis in he lase abla ed SnO2 ilms as seen om ou
XPS and XAS da a. These Sn- ela ed de ec s migh as well
con ibu e o he o e all magne ic in e ac ions and he o al
magne ic momen , depending on hei speci ic loca ions.
5 Conclusions
Ul a- hin SnO2 ilms exhibi oom- empe a u e e omag-
ne ism wi h a la ge magne ic momen , whe eas hicke ilms
display diamagne ic beha io like hei bulk coun e pa s.
This sugges s he exis ence o a c i ical hickness equi ed
o e omagne ism o eme ge. Ou s udy e eals dis inc
di e ences in O/Sn acancies and de ec s be ween hin
and hick ilms. An excep ionally high Cu ie empe a u e
TC exceeding 800 K was obse ed. Ou heo e ical calcula-
ions p edic a high TC, con i ming ha O/Sn acancies and
de ec s a e he p ima y con ibu o s o he magne ic momen
in undoped SnO2 ilms. The expe imen ally de e mined TC
is e en highe han ou heo e ical es ima e, sugges ing ha
in addi ion o oxygen acancies, Sn acancies and de ec s
play a c ucial ole in enhancing he o al magne ic momen .
Fu he mo e, he es ima ed exchange in eg al o SnO2
ilms is o he same o de as ha ound in ansi ion me als,
ein o cing he signi icance o de ec -induced magne ism in
hese ma e ials.
Supplemen a y In o ma ion The online e sion con ains supplemen a y
ma e ial a ailable a h p s : / / d o i . o g / 1 0 . 1 0 0 7 / s 0 0 3 3 9 - 0 2 5 - 0 9 0 3 1 - 7 .
Acknowledgemen s The au ho s acknowledge he inancial suppo
om he GACR (P ojec No. 22–21547 S) and he MEYS (P ojec
CZ.02.01.01/00/22_008/0004572). N. Q. Huong would like o hank
g an RCG23-007 (WVURC-MURC 23–049). We hank M. Kiaba
and T. Q. Nhu o some echnical suppo and A. Nebojsa o his
help wi h hickness measu emen s. The CzechNanoLab P ojec No.
LM2018110, unded by MEYS CR, is g a e ully acknowledged o
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